نتایج جستجو برای: conifer needles
تعداد نتایج: 9417 فیلتر نتایج به سال:
The potential differentiations in litter chemistry among native and non-native trees are poorly understood. We compared the chemical composition of leaf litterfall of 11 exotic tree species, e.g. coniferous: Abies cephalonica, A. grandis, A. procera, Chamaecyparis pisifera, Pinus peuce, Pseudotsuga menziesii, Thuja plicata, and deciduous: Acer rubrum, A. saccharum, Betula alleghaniensis and Que...
BACKGROUND AND AIMS Globally, conifer dominance is restricted to nutient-poor habitats in colder, drier or waterlogged environments, probably due to competition with angiosperms. Analysis of canopy structure is important for understanding the mechanism of plant coexistence in relation to competition for light. Most conifers are shade intolerant, and often have narrow, deep, conical crowns. In t...
Within-stand variation in understory species composition and biomass was studied in 16 even-aged stands of mixed Red Alder Sitka Spruce Western Hemlock (Alnus rubra Picea sitchensis Tsuga heterophylla) forest. The sites were upland sites, and the stands were 28-39 years old. We compared understory within three categories of microsite types: Red Alder-dominated, conifer-dominated, and mixed alde...
Mycorrhizal root nodules occur in the conifer families Araucariaceae, Podocarpaceae, and Sciadopityaceae. Although the fossil record of these families can be traced back into the early Mesozoic, the oldest fossil evidence of root nodules previously came from the Cretaceous. Here we report on cellularly preserved root nodules of the early conifer Notophytum from Middle Triassic permineralized pe...
Background and Aim: Considering the fact that injecting drug is the most common way of HIV transmission and having the point in mind that in spite of syringes availability, many of the IDUs still continue sharing needles, determining behaviors which lead them not to use HR packages seems invaluable. Determining the influential factors in sharing needles among IDUs who are Kermanshah's DIC clien...
In the context of ongoing climatic warming, certain landscapes could be near a tipping point where relatively small changes to their fire regimes or their postfire forest recovery dynamics could bring about extensive forest loss, with associated effects on biodiversity and carbon-cycle feedbacks to climate change. Such concerns are particularly valid in the Klamath Region of northern California...
The composition, integrity, and architecture of the macromolecular matrix of cell walls, collectively referred to as cell wall ultrastructure, exhibits variation across species and organs and among cell types within organs. Indirect approaches have suggested that modifications to cell wall ultrastructure occur in response to abiotic stress; however, modifications have not been directly observed...
Particulate Hg (pHg) is a component of smoke from biomass burning and has the potential for local redeposition. Throughfall (precipitation collected beneath a conifer or deciduous canopy) and open precipitation samples were collected pre- and postfire in 2005 and 2006 using passive precipitation collectors across the Superior National Forest, located in northern Minnesota, USA. Samples were col...
To assess the potential impact of conifer encroachment on soil organic carbon (SOC) dynamics and storage in montane aspen-conifer forests from the interior western US, we sampled mineral soils (0–15 cm) across the aspen-conifer ecotones in southern and northern Utah and quantified total SOC stocks, stable SOC (i.e., mineral-associated SOC (MoM)), labile SOC (i.e., light fraction (LF), decomposa...
BACKGROUND Long-term studies allow capture of a wide breadth of environmental variability and a broader context within which to maximize our understanding of relationships to specific aspects of wildlife behavior. The goal of our study was to improve our understanding of the biological value of dense conifer cover to deer on winter range relative to snow depth and ambient temperature. METHODO...
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